In vitro detection of anti-thyroglobulin antibody forming cells from the lymphocytes of chronic thyroiditis patients and analysis of their regulation.

Anti-thyroglobulin (anti-Tg) antibody forming cells were detected by plaque forming cell (PFC) assay, using B cells depleted of sheep erythrocyte (SRBC) binding cells and T cells separated without SRBC interaction. When 2 x 10(5) non-T cells were combined with the same number of T cells from chronic thyroiditis patients, more than 20 PFC were detected; few, if any, PFC developed from normal lymphocytes. T cells were generally needed to produce quantifiable PFC, suggesting that helper T cells are required for this autoantibody formation. A positive relationship existed between the number of PFC and the serum anti-Tg antibody titres of the same patients. The generation of Tg-specific PFC from patient lymphocytes was markedly suppressed by normal T cells or T cells from patients whose lymphocytes did not produce PFC. The same level of suppression was also seen on the addition of culture supernatant from Tg antigen stimulated T cells. Autologous T cells, from patients whose lymphocytes produced PFC, did not show such suppressor effects, suggesting that in chronic thyroiditis patients, the regulatory T cell function preventing anti-Tg autoantibody formation is impaired.